Police have pledged to fight a landmark ruling which could force officers to reveal the locations of their secret car-tracking cameras.

Millions of number plates a year are read by automatic number plate recognition (ANPR) cameras as officers keep tabs on criminals using the roads in Sussex.

But the exact number, and their locations, has always been protected by the force with national experts saying releasing the information would damage investigations into organised crime – allowing offenders to know where they can drive without being detected.

However an information ruling by one of the highest groups in the land could mean it has to reveal this data to all who request.

Sussex Police is now working with the Association of Chief Police Officers (Acpo) to appeal the decision.

It comes after a two-year battle by Steven Mathieson, news editor at Guardian Government Computing.

He requested the locations of the cameras in Devon and Cornwall under the Freedom of Information Act in July 2009. The force refused on the grounds that if it revealed where they were stationed it would “be likely to prejudice the prevention of crime”.

It blocked the move after an internal review, a decision which was supported by the Information Commissioner.

Mr Mathieson then appealed to the Information Rights Tribunal which has now found in his favour, ordering that the information be disclosed within 35 days.

The decision is known to have raised major concerns within Acpo and particularly for the Police Service of Northern Ireland.

Fearing it could leave other forces across the country open to revealing similar information, Devon and Cornwall Police has confirmed it will challenge the ruling in the Court of Appeal.

Sussex Police has a dedicated team using both static and vehicle cameras to “deny criminals the use of the roads in Sussex”.

The technology is used to intercept vehicles used in criminal activity, gather intelligence and trace vulnerable and missing people.

Figures revealed under Freedom of Information confirm the force carried out 233 million vehicle number plate checks in 2009.